Airborne exposure to toxic organic substances (TOS) in atmospheric aerosol, including nitrophenols from wildfire and biomass burning, and bisphenols from plastic incineration and degradation of plastics in sea spray aerosol, pose a potential significant risk to humans and the environment, and may be exacerbated in the future because of more frequent intense droughts and continued poor waste management practices. In our work, we study the heterogeneous and multiphase photochemical and oxidative degradation reactions and kinetics that affect the lifetimes of TOS in aerosol. Our previous work showed that the OH radical uptake by nitroguaiacol, a toxic byproduct of lignin decomposition, is suppressed at longer OH exposures (i.e., [OH]×time) and the oxidative degradation rate of methyl nitrocatechol, a biomass burning secondary organic aerosol marker, is suppressed at higher relative humidity, both due to competitive coadsorption of OH radicals and water at the surface. We also demonstrated that heterogeneous OH oxidation enhances the hygroscopicity of methyl nitrocatechol aerosol but the effects of oxidation on the hygroscopicity of the particles is masked in the presence of more hygroscopic inorganic salts. More recently, we have been investigating the degradation kinetics and lifetimes of the persistent plastic pollutant, bisphenol A (BPA) in the presence of OH and in the presence of a photosensitizer under solar-simulated light in an aerosol flow tube employing (extractive electrospray ionization) high resolution time-of-flight chemical ionization mass spectrometry. We study BPA degradation in simple single- and binary-component aerosol as well as complex representative sea spray aerosol produced from a marine aerosol reference tank with controlled biology. In honor of the work of Prof. Vicki Grassian, I will discuss highlights from these works and new insights into the analysis of plastic degradation in sea spray aerosol.

Old and new insights of heterogeneous and multiphase oxidative processes affecting the lifetimes of toxic organic substances in biomass burning and sea spray aerosol

2019 Fall National Meeting

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